<ARTICLE>     5
<MULTIPLIER>  1,000

       
                                   
<PERIOD-TYPE>                               6-MOS
<FISCAL-YEAR-END>                     DEC-31-1998
<PERIOD-END>                          JUN-30-1998
<CASH>                                    131,119
<SECURITIES>                              278,111
<RECEIVABLES>                             234,009
<ALLOWANCES>                                2,548
<INVENTORY>                               101,379
<CURRENT-ASSETS>                          824,202
<PP&E>                                  1,766,754
<DEPRECIATION>                            601,548
<TOTAL-ASSETS>                          2,132,072
<CURRENT-LIABILITIES>                     398,851
<BONDS>                                         0
<COMMON>                                    1,409
<PREFERRED-MANDATORY>                           0
<PREFERRED>                                     0
<OTHER-SE>                              1,615,082
<TOTAL-LIABILITY-AND-EQUITY>            2,132,072

<SALES>                                   654,951
<TOTAL-REVENUES>                          654,951
<CGS>                                     358,951
<TOTAL-COSTS>                             358,951
<OTHER-EXPENSES>                          223,030
<LOSS-PROVISION>                                0
<INTEREST-EXPENSE>                              0
<INCOME-PRETAX>                            83,355
<INCOME-TAX>                               20,878
<INCOME-CONTINUING>                        62,477
<DISCONTINUED>                                  0
<EXTRAORDINARY>                                 0
<CHANGES>                                       0
<NET-INCOME>                               62,477
<EPS-PRIMARY>                                0.44
<EPS-DILUTED>                                0.44